Odd battery, auto size

[cmac2012]

One of my clients has a large rental that had the beginnings of an emergency, earthquake type lighting system installed. It was to have a 12 volt back up that would be kept routinely charged. This was installed (partially) by her previous maintenance man who expired from cancer several years back.

It was never finished, she has no interest in finishing it, not sure she really understood it from the git-go. Among the uninstalled parts was a battery labeled 12v, 65 AmpHour. It looks like a typical auto battery but has unusual posts, about a quarter inch looking thread rod sticking up an inch or so for each terminal.

It says, "factory sealed, do not open vent caps or it will void the warranty." I'm thinking any warranty is history at this point (4 years later, no receipt) so I opened them and only one has any visible water in it, and that one is low. My voltmeter shows a charge of 12.01 volts (?!).

Beats the hell out of me. I have a step van with a chev 6.2 diesel - two batteries - both of which need replacing, amazing they lasted about 10 years. It's largely on mothballs, but still valuable, I start it once every few weeks, it has a 2' x 3' solar cell on top, I installed it, that keeps the batteries topped off. I'm hoping to use this for one of them.

I can't find any info on the web. My guess is I should top them off with distilled water or highly filtered anyway, charge it up and see what happens. I'm hoping the fact that it's never been used will mitigate any damage from being low on water. What I don't understand is why it would be dry at that age, no use, if the vent caps are never supposed to be removed.